Abstract: An expansion-distribution assembly for simultaneously throttling, mixing, and distributing refrigerant fluid upstream of a heat-absorbing component (e.g., an evaporator) of a heat pump system. The expansion-distribution assembly comprises a valve-nozzle adjustment device which moves a pin relative to a nozzle chamber to vary flow-characteristics therethrough. The pin is moved during operation of the heat pump system (based on, for example, pressure and temperature data) to dynamically customize the valve-nozzle for the current load of the system.